The invention relates to a support for supporting a substrate in a chamber and related methods.
In the manufacture of integrated circuits, a substrate is processed by a plasma of process gas in a chamber. The substrate is typically supported in the chamber by a support, a portion of which may comprise a dielectric material covering an electrode. The electrode may be charged to electrostatically hold the substrate, to energize the process gas in the chamber, or to do both. In addition, the support may comprise a heater to heat the substrate, or a heat exchanger, such as for example, channels through which heat transfer fluid may be circulated to heat or cool the substrate. In addition, a heat transfer gas, such as helium, may be introduced through a conduit in the support to below the substrate to enhance heat transfer rates to and from the substrate.
Electrostatic chucks are typically either Coulombic or Johnsen-Rahbek type. Coulombic electrostatic chucks use a dielectric material having a higher electrical resistance to generate coulombic electrostatic forces. Johnsen-Rahbek type (JR) electrostatic chucks utilize dielectric layers that are made of a semiconducting material, for example one or more semiconducting ceramics such as aluminum nitride or oxide ceramics, that at least partially conducts electricity. The JR chucks often provide higher electrostatic clamping forces for a lower applied voltage.
A disadvantage of electrostatic chucks, particularly the Johnsen-Rahbek type electrostatic chucks, is that they may result in sporadic micro-arcs within the plasma in the chamber. Additionally, the plasma can often become unstable or destabilize with these chucks. The micro-arcs and destabilized plasmas can result in significant damage to a substrate and can also cause sporadic and temporary loss of chucking force. The micro-arcs can also deteriorate the components in the process chamber, such as the dielectric materials.
Another problem with conventional electrostatic chucks is that they may result in an unevenly distributed plasma sheath. In a typical process chamber, a gas distributor introduces process gas and a plasma is energized, for example by applying an RF voltage to a cathode supporting the substrate and by electrically grounding an anode to form a capacitive field in the process chamber. An electrostatic chuck above the cathode electrostatically holds the substrate. However, the dielectric material in the electrostatic chuck can affect electrical coupling from the cathode to the plasma which can result in an unevenly distributed plasma sheath. The lack of spacial uniformity of the plasma sheath can result in inadequately and inconsistently processed substrates.
In another chamber design, a relatively thick insulator shield is used to electrically isolate a peripheral cathode portion. However, the insulator shield may reduces the RF current between the cathode and the plasma at the periphery of the substrate. The resultant non-uniform plasma across the surface of the substrate can cause the peripheral portion of the substrate to be non-uniformly processed relative to the central portion. Plasma processing may also be nonuniform when the cathode does not extend all the way to the peripheral edge of the substrate, as for example in chambers where the cathode has a diameter slightly smaller than that of the substrate. As a result of these effects, the peripheral substrate portion often has reduced yields.
Thus, there is a need for a chamber capable of providing a uniform plasma across the substrate surface, and in particular, across the peripheral edge of the substrate. There is also a need for a chamber that may be used to extend the plasma beyond the peripheral edge of the substrate. There is a further need to stabilize the plasma and reduce arcing, especially when using electrostatic chucks.
The present invention satisfies these needs. In one aspect the invention comprises a support capable of supporting a substrate in a chamber. The support comprises a dielectric covering an electrode, the dielectric having a surface capable of receiving the substrate, a conductor capable of capacitively coupling with the electrode, and a voltage supply adapted to supply an RF voltage to the conductor.
In another aspect of the invention, a process chamber capable of processing a substrate in a plasma comprises a gas distributor adapted to introduce process gas in the chamber, a dielectric covering an electrode, the dielectric having a surface capable of receiving the substrate, a conductor capable of capacitively coupling with the electrode, and a voltage supply adapted to supply a gas energizing voltage to the conductor.
In another aspect of the invention, a process chamber capable of processing a substrate in a plasma comprises a gas distributor adapted to introduce process gas in the chamber, a dielectric covering an electrode, the dielectric having a receiving surface adapted to receive the substrate, a conductor comprising a first conductor and an interposer between the first conductor and the dielectric, and a voltage supply capable of supplying a gas energizing voltage to the electrode.
In another aspect of the invention, a support capable of supporting a substrate in a chamber comprises a dielectric covering an electrode, the dielectric having a surface capable of receiving the substrate, a connector capable of supplying a voltage to the electrode, and a conductor capable of capacitively coupling with the connector.
In another aspect of the invention, a process chamber capable of processing a substrate in a plasma comprises a gas distributor adapted to introduce process gas in the chamber, a dielectric covering an electrode, the dielectric having a surface capable of receiving the substrate, a connector capable of supplying a voltage to the electrode, a conductor capable of capacitively coupling with the connector, and a voltage supply adapted to supply a gas energizing voltage to the conductor or to the electrode.
In another aspect of the invention, a method of processing a substrate in a process zone comprises supporting the substrate on a support in the process zone, the support comprising a dielectric covering an electrode, distributing process gas in the process zone, and energizing the process gas by coupling RF power from the electrode to the energized gas without supplying an RF voltage directly to the electrode.
In another aspect of the invention, a method of processing a substrate in a process zone comprises supporting the substrate on a support in the process zone, the support comprising an electrode, introducing process gas into the process zone, supplying a voltage to a conductor below the electrode, and capacitively coupling the voltage from the conductor to the electrode to energize the process gas.
In another aspect of the invention, a method of processing a substrate in a process zone comprises supporting the substrate on a support in the process zone, the support comprising an electrode, introducing process gas into the process zone, supplying a gas energizing voltage to the electrode through a connector, and capacitively coupling the gas energizing voltage from the connector to a conductor below the electrode.